1. Field of the Invention
The present invention relates to a general-purpose push switch used as a button in electronic equipment such as a cellular phone or a multidirectional input device for operation of electronic equipment such as a cellular phone.
2. Description of the Related Art
Regarding the drawing for a conventional multidirectional input device, FIG. 18 shows the main part of a conventional multidirectional input device.
A case 50 is a plastic box with an opening at the top. It has an octagonal bottom wall 50a; projections 50d spaced at regular intervals which protrude upwards from the bottom wall 50a; a side wall 50b standing upwards from the side edge of the bottom wall 50a; and notches 50c made at intervals of approximately 90 degrees in the side wall 50b. 
A first fixed contact 51 consists of a contact part 51a located at the top end and a terminal 51b extending outwards from the contact part 51a; the first fixed contact 51 is embedded in the bottom wall 5a with the contact part 51a exposed in the center of the bottom wall 50a. A common contact 52 consists of a semicircular arch contact part 52a and a terminal 52b extending outwards from the contact part 52a. This common contact 52 is embedded in the bottom wall 50a with the bottom wall 50a exposed on the surface of the bottom wall 50a, surrounding the contact part 51a of the first fixed contact 51.
A first movable contact 53 is made of metal. It has the shape of a dome and rests on the bottom wall 50a with its periphery guided by the projections 50d. With the first movable contact 53 in place, its side edge 53a remains in contact with the contact part 52a of the common contact 52 and its top 53b faces the contact part 51a of the first fixed contact 51. The first fixed contact 51, common contact 52 and first movable contact 53 constitute a push switch S.
A guide 54 is made of plastic and has virtually the shape of a dome. It has a base 54b with a through hole 54a at the top; an arm 54c supported on one side, extending towards the center from the base 54b; and a spacer 54d engaged with the arm 54c. This guide 54 is fixed by the base 54b engaged with the projections 50d. Once the guide 54 is fixed in this way, the arm 54c faces the top of the first movable contact 53.
A coil spring 55 is made of a conductive metal. It stands on the bottom wall 50a near the side wall 50b, surrounding the first movable contact 53.
A cover 60 is an octagonal flat plate with a through hole 60a in the center. A second fixed contact 61 consists of a contact part 61a at the top end and a terminal 61b bent at right angles from the contact part 61a. The second fixed contact 61 is embedded in the cover 60 every approximately 45 degrees with the terminal 61b exposed on the lower face of the cover 60. The cover 60 and the second fixed contact 61 are arranged so as to cover the opening of the case 50, and a U-shaped metal leg 62 is used to fix them between the case 50 and the leg 62.
A handle 64 consists of a driving body 65, a second movable contact 66 embedded in the driving body 65, and a control shaft 67 spline-connected with the driving body 65. The driving body 65 is almost cylindrical and has in its center a through hole 65a which runs from the top to the bottom and has an oval bottom. The second movable contact 66 is a conductive metal ring disc with outward-stretching projections 66a arranged at intervals of 90 degrees. The second movable contact 66 is embedded at a level almost equal to the middle of the height of the driving body 65. Made of plastic, the control shaft 67 has a cylinder 67a and an oval jaw 67b at the bottom of the cylinder 67a. The cylinder 67a is inserted through the through hole 65a from below the driving body 65 and the jaw 67b is spline-connected with the driving body 65 to control the rotation of the control shaft 67.
The handle 64 is tiltably housed in the case 50 and the top 65b of the driving body 65 is tiltably supported by the through hole 60a of the cover 60. The bottom 67c of the control shaft 67 is in contact with a spacer 54d; the second movable contact 66 is held pressed up by the coil spring 55 to be pressed against the contact part 61a of the second fixed contact 61. Here, since the second movable contact 66 is in contact with the coil spring 55, there is always continuity between the second movable contact 66 and the common contact 52. The second fixed contact 61 and the second movable contact 66, held pressed by the coil spring 55, constitute a tilt switch S6 which normally stays closed. The projections 66a of the second movable contact 66 engage with the notches 50c in the side wall 50b to prevent rotation of the entire handle 64.
Next, how the conventional multidirectional input device operates will be explained. As the control shaft 67 is tilted in a desired direction, the handle 64 tilts on a fulcrum C which is the point of contact between the contact part 61a of the second fixed contact 61 and the second movable contact 66 on the side opposite to the tilting direction, and the tilt switch S6 on the side of the fulcrum C stays ON while the tilt switch S6 on the opposite side turns OFF. The coil spring 55""s part on the side opposite to the fulcrum C is contracted.
Also, upon tilting of the handle 64, the bottom 67c of the control shaft 67 bends down the arm 54c through the spacer 54d so that the first movable contact 53 is pressed and the push switch S5 turns ON.
Then, as the pressure on the control shaft 67 is released, the coil spring 55 returns to its original state and the second movable contact 66 returns to its original state as well; as a consequence, the handle 64 returns to its neutral position and the tilt switches S6 all turn ON. The arm 54c and the first movable contact 53 return to their original state due their elastic force so the push switch S5 turns OFF again.
When the control shaft 67 is pushed in axially with the handle 64 in its neutral position, the control shaft 67 moves down as guided by the through hole 65a of the driving body 65, which presses the first movable contact 53 to turn ON the push switch S5. Meanwhile, all the tilt switches S6 stay ON. Then, as the pressure on the control shaft 67 is released, the arm 54c and the first movable contact 53 return to their original state due to their elastic force so the push switch S5 turns OFF again and, the control shaft 67 is pushed back by the arm 54c and returns to its original state.
In the conventional multidirectional input device, which has the above-mentioned constitution, there has been a problem that the overall height of the device has to be large enough to accommodate the height of the coil spring 55 in order to ensure that continuity is established between the second movable contact 66 and the common contact 52 through the coil spring 55.
Another problem is that since the coil spring 55 is located near the side wall 50b and the common contact 52 has to be placed around the first movable contact 53, the device size should be relatively large.
A further problem is that the shape of the common contact 52 must be complicated in order to ensure that the common contact 52 touches the coil spring 55. In addition, since the arm 54c and spacer 54d lie between the first movable contact 53 and the control shaft 67, the overall height should be relatively large.
In view of the above problems, the present invention provides a low-profile, compact, multidirectional input device which does not use the coil spring 55.
As a first solution to the above problems, the present invention provides a multidirectional input device comprising: a casing having a bottom wall with a common contact; a first fixed contact held above and opposite the bottom wall by the casing; a first movable contact which is located between the bottom wall of the casing and the first fixed contact, and tiltably housed in the casing and can be brought into or out of contact with the first fixed contact; a handle having the first movable contact, which can be tilted in many different directions; and a second movable contact which touches the common contact, wherein the first movable contact has a contact area which is to touch the second movable contact; when the handle is tilted, the first fixed contact and the first movable contact touch each other and to establish continuity between the first fixed contact and the common contact through the first movable contact, the contact area and the second movable contact, generating a first electric signal.
As a second solution, in a multidirectional input device according to the present invention, the bottom wall of the casing has a second fixed contact and the second movable contact can be brought into contact with the second fixed contact when pressed, and when the handle is tilted, the first electric signal is generated and the second fixed contact and second movable contact touch each other and to establish continuity between the common contact and the second fixed contact, generating a second electric signal.
As a third solution, in a multidirectional input device according to the present invention, the casing has an interface which is facing and opposite the bottom wall with the first movable contact between the bottom wall and it, and when the handle is in its neutral position, it is pressed against a lower face of the interface due to an elastic force of the second movable contact.
As a fourth solution, in a multidirectional input device according to the present invention, the handle or the interface has an axially protruding projection, and when the interface and handle touch each other through the projection and with the handle in its neutral position, the first movable contact is out of contact with the first fixed contact.
As a fifth solution, in a multidirectional input device according to the present invention, the first movable contact has the projection (ridge) opposite the interface.
As a sixth solution, in a multidirectional input device according to the present invention, when the handle is tilted on the projection as a first fulcrum, the first fixed contact and first movable contact touch each other, and when it is tilted on the point of contact between the first fixed contact and the first movable contact as a second fulcrum, the second fixed contact and second movable contact touch each other.
As a seventh solution, in a multidirectional input device according to the present invention, the interface is a metal plate which is held and joined together with the first fixed contact by a plastic support and the handle has escapes through which convexes on the bottom wall side of the support can come and go when it is tilted.
As an eighth solution, in a multidirectional input device according to the present invention, the casing comprises a lower case having the bottom wall, and the support as an upper case separate from the lower case; the first fixed contact fitted to the upper case is fixed on the lower case to join the lower case and the upper case together.
As a ninth solution, in a multidirectional input device according to the present invention, when the handle is pushed axially, the second fixed contact and the second movable contact touch each other to establish continuity between the common contact and the second fixed contact.
As a tenth solution, in a multidirectional input device according to the present invention, the second movable contact comprises a dome-shaped leaf spring, and the contact area of the first movable contact on the handle is semispherical, protruding towards the bottom wall; and an outer semispherical surface of the contact area touches the second movable contact.
As an eleventh solution, in a multidirectional input device according to the present invention, the second movable contact comprises a dome-shaped leaf spring, and the contact area of the first movable contact on the handle has a flat portion facing the second movable contact; and the flat portion touches a top of the second movable contact.
As a twelfth solution, in a multidirectional input device according to the present invention, the second movable contact comprises a dome-shaped leaf spring, and the contact area of the first movable contact on the handle has a square or ring ridge protruding towards the second movable contact; and the ridge touches the top of the second movable contact.
As a thirteenth solution, in a multidirectional input device according to the present invention, the second movable contact comprises a dome-shaped leaf spring, and the contact area of the first movable contact on the handle has plural convexes protruding towards the second movable contact; and the convexes touch the top of the second movable contact.